Can this VFD power a 1 HP Bridgeport

I read that label as capable of 1HP OUTPUT.

Shawn

I'm sure it will work fine. I have a Magnetek 1 Hp-rated VFD labeled for 3-phase input only, and it has worked fine for a number of years on a 1 Hp Bridgeport. I only have single phase service.

I have it set for 1 sec accel, 3/4 second decel.

Yes, I put a pot and an on-off switch where the original motor drum switch went.

I have a 220 V outlet that is used for a couple different machines, and is powered on/off by a breaker.

The mill base doesn't vibrate much, ever. But, I put mine above the spindle on the wall, to reduce catching the chips that get flung all over. Don't use 10-32 in cast iron. It is better to use coarser threads in such crumbly stuff, like 1/4-20.

Jon

Well, 1HP is approx 0.75KVA, so 1.6KVA should work fine. I would certainly opt for a separate switch and mount the VFD somewhere where it is not likely to be damaged. If its possible, you should also fit a separate speed control pot - I found the keypad not very convenient. I fitted (Mitsubishi) VFDs to my Centec; one for the main drive and one for the table. The VFDs are in the base and the separate switches and pots are mounted in a small plastic box on the end of the table, where they are very accessible.

OK, great.

good, thanks

I think that I will try to keep and use that drum switch for controlling the VFD.

OK.

OK, good point on the fine vs coarse thread issue. I would never think of that, I try to use 10-32 everywhere, but this is obviously a good exception.

i

I left my drum switch there, too, as it was also the junction box for the motor wires. I made a little box with a toggle switch and a "knobpot" that attaches to the housing of the drum switch.

Jon

I would think so.

1-2 seconds.

Yes. Remove the 220 wireing from the existing drum switch and use it. Its close to the head where you need it. Particualry in tapping operations.

Plug works fine..though a breaker/fuse disconnect is proper.

Mount it where coolant and chips wont splash it.

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It's more for other stuff, such as (as you said) making three phase, also acceleration, braking, overload protection, etc.

i

According to Ignoramus584 :

Great!

:-)

Except that I can't get to the manual sub-pages.

"Forbidden". :-)

Since it is rated for single-phase input and 1HP output (as confirmed from the labels in your photo), I would say that you should have no problems.

It looks good -- though I would probably use a bit larger VFD, just as I intend to run my 2HP Bridgeport (same period, but 2J variable speed head) from a 3HP one -- but mine is not spec'd to run from single phase at full rating, while yours apparently is.

Experiment. Put the largest cutting tool you have in the spindle, and set the belt of the maximum speed (assuming that is not to fast to run the tool -- don't use something unbalanced like a boring head, but pick something like a face mill which can take the speed.

Then start and stop it a few times. If it locks up with an overcurrent alarm, increase the accel/decel times. Go on up to perhaps

25% over the minimum time which won't trip the overcurrent. (Note that you may wish to add the braking resistor before running these tests if it is not already part of the VFD.) The settings from the factory are probably acceptable already. You might want to shorten the accel/decel times if you are doing tapping without a TapMatic or Procunier style tapping head.

I would wire an external switch -- ideally the drum switch which is already in series with the motor lead. This would have two benefits:

1) It would keep you from having to reach past the machine to the wall-mounted VFD to start or stop the machine, thus increasing safety -- especially when you need to *stop* it in a hurry. 2) It would keep you (or someone else who did not know better) from throwing that switch while it was still in series with the motor, which could damage the VFD.

This is why I tried to download part of the manual -- the wiring section, to make sure that it supported that form of controls.

I would also wire a remote pot for speed control (another reason for looking at the VFD's wiring manual). Put it in a small metal box just below the switch, or just beside it, where it also is easy to reach.

A 240V plug -- ideally twist-lock just to be a bit higher current -- should be fine for this. If you unplug the VFD from the wall, and bring the plug over to where you can keep a foot on it while working on the wiring of the machine, it should help keep some "helpful" person from plugging it back in to save you some steps -- before you are through wiring. :-)

I would tend to mount it on a metal plate stood off from the wall a bit. Several benefits:

1) It is out of the flow of chips when you are cutting energetically. They fly in *all* directions, including up. (Mount it so it is behind the casting away from the flow of chips.) Really hot chips could melt the plastic of the housing, and more important *any* metal chips could work their way inside (there needs to be airflow for heat control), and short between pads damaging some or all of it. 2) It is clear of the vibrations, which could cause premature component failure. 3) It is less likely to get hit by a heavy workpiece as you are moving something onto or off of the mill's table. (Mount it high enough so anything on the table won't reach it. 4) You have the small inductance of the extra length of three phase cable to reduce voltage spikes in the motor somewhat.

Enjoy, DoN.

Some comments on Don N's advise interspersed, unrelated material removed.

no no - while you COULD use the drum switch, I'd recommend you use a small toggle switch, SPST to signal "reverse" to the control - you don't want to actually break the line between the motor and the VFD while under power or you are at some risk of damaging the VFD - wires from the VFD to the motor should be as short as practical and uninterrupted. Remove the drum switch entirely.

see note above about "as short as practical" - I don't know the exact layout of a bridgport but my vague recollection is that there is space inside the base casting that is empty - that would be a good close location that is well protected. With a remote control, you won't need access to the unit. Alternatively, you could mount it on the side of the unit (out of the chip stream as don suggested) - all the enclosed units I've seen are pretty well protected against stuff getting inside, I'd be more worried about a wire longer than 3 to 5 feet than chips.

4 is actually not correct - per the manual for these things, the longer wires tend to cause ringing and problems, not damping.

According to William Noble :

I was suggesting removing the drum switch from the leads from the VFD to the motor and rewiring it to provide the run/stop/reverse commands to the VFD. Thus the drum switch would *not* be breaking the feed from the VFD to the motor, but rather commanding the VFD to start/stop/reverse. Most VFDs can be set up to either latch signals from pushbuttons or to accept forward and reverse commands from one spdt section of the drum switch (there are two of them plus the on/off/on lead in addition which would not be used here), so the habits of using the switch would remain unchanged whether using the VFD equipped machine at home, or having to use another Bridgeport somewhere else. (This should include the internalizing of the need to interchange reverse and forward when the back gears are engaged, since they reverse the spindle rotation.)

*If* you can get to it. In my Series I Bridgeport (BOSS-3 CNC version), there is no access to inside the base casting, unless you hang it from a hoist and risk your life working under the suspended machine.

Some of the earlier machines had a door in the upper half of the base casting, on the left side as you face the machine. This was used to house a coolant pump, with the base containing the coolant reservoir. The upper area was too small to hold any of *my* VFDs, but it *might* hold the little 1HP one which Iggy has.

Well ... I'm using one 7.5 HP Westinghouse/Teco VFD (mounted near the Bridgeport) to run another mill -- a Nichols horizontal mill -- which is across the shop (ex 2-car garage), with somewhere between twelve and eighteen feet of cable. It produces *no* problems -- the VFD and the motor are totally happy.

[ ... ]

As I said -- I've had no problems running through a 12 to 18 foot cable.

The series inductance of the cable wires and the parallel capacitance of those wires running in the same jacket form a poor transmission line, and tend to reduce the spikes somewhat compared to running directly into the motor's windings, which are *all* inductive.

Granted -- the VFD which I am using is rather overkill for the

1HP motor on the Nichols.

But certainly the run from the motor to the wall should not be long enough to produce problems, even with the smaller VFD which Iggy has. I would go from the motor to the ceiling, and down the wall to get to the VFD, and have no worries.

Enjoy, DoN.

Thanks to all. I decided to wire it in two stages: first without disrupting the mill's wiring, just on a temporary basis, and then I will rewire it, either with the drum switch to control thr VFD, or with a pendant.

i

Finally figured out how to set up the VFD, reset everything to factory defaults, set up acceleration to 1s, deceleration to 1s, max frequency

60 Hz, min frequency 0, panel potentiometer speed control and keypad start/stop operation. Tried it with a free 1 hp motor and it all works fine. Magically, the motor decelerates even without a brake resistor (WTF would I then need a brake resistor?). i

I've never used one. Maybe for a really quick stop? Motion control?

Pete Keillor

If you need to stop the load real fast or if what you are stopping has a lot of inertia. It's a lot harder to stop the lathe with the 8" 4-jaw chuck and the 200lb lump of steel in it than just the motor :-)

I can sometimes trip one of the resistorless inverters I use on a lathe if I try to stop too large a lump from too high a speed. No big problem, I just press the stop button again and then it's happy.

Mark Rand RTFM

I am totally lost on this one, it is a shock to me. Something does not make sense. The 1s deceleration is awesome, by the way.

i

OK, so, it seems that when I use this VFD to power the mill, the pulleys, spindle etc, inertia may give me a different picture. (though I am unlikely to have a situation like with a lathe).

Now I "get it" a little better. I already have two 50w rated, 100 Ohm resistors. Together they will give me 200 Ohm, 100w rating, slightly exceeding the factory spec'ed 200 Ohm, 80w resistor.

i

Turn on the option to display DC bus voltage, if your drive has that ability. You'll see the voltage rise when the motor is decelerating. The resistor is only necessary if the decelerating motor pumps enough energy back into the filter caps to push the bus voltage beyond the shutdown limit.

Ned Simmons

assuming a 1750 motor..set max freq to 120, then do a high speed reverse at 120 hz. If you dont get a OU (over load alarm) dont worry about the braking resister

Gunner

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Gunner, thanks. I will experiment, I think that it is relatively clear to me at this point what is the issue with braking resistors (which was explained by Ned and others).

You mentioned 120 Hz. I could try it with the motor I have on the bench, though I would not try it with the mill.

Do you know how fast one could spin a typical 3 phase motor as a function of its rated RPM, before it self destructs? My VFD goes up to

400 Hz, I think that it would be fun to make a video of a self destructing motor. 3,450 * 400/60 = 23,000 RPM. i